Certain refrigerator appliances include sealed systems for cooling chilled chambers of the refrigerator appliance. The sealed systems generally include a compressor that generates compressed refrigerant during operation of the sealed system. The compressed refrigerant flows to an evaporator where heat exchange between the chilled chambers and the refrigerant cools the chilled chambers and food items located therein.
A typical compressor, such as a reciprocating or rotary compressor, includes a piston which is driven by a motor. Motion of the piston compresses refrigerant, which is then flowed from a chamber in which the piston is housed. A reciprocating compressor typically includes a piston which has a linear motion, a chamber in which the piston is housed, an inlet (or suction) passage for supplying refrigerant to the chamber, and an outlet (or discharge) passage for flowing the compressed refrigerant from the chamber. During operation, the piston moves in a reciprocating manner along the linear path between an optimal parking position, such as top or bottom dead center position, and various other positions. A rotary compressor typically includes a piston which has an eccentric rotational motion, a chamber in which the piston is housed, an inlet (or suction) passage for supplying refrigerant to the chamber, and an outlet (or discharge) passage for flowing the compressed refrigerant from the chamber. During operation, the piston moves along an eccentric rotational path between an optimal parking position, such as top or bottom dead center position, and various other positions.
One issue that can occur for many compressors is refrigerant backflow when the motor is turned off. In particular, refrigerant can flow back from the discharge passage into the chamber. This can cause additional energy consumption during a refrigeration cycle and result in inefficient cooling and energy loss. One solution for reducing or preventing such backflow is to place the piston at an optimal parking position, such as top dead center, when the motor is turned off and movement of the piston is stopped. This would completely or substantially seal the inlet and outlet passages and reduce or prevent backflow. However, determination of when the piston is at this optimal parking position in order to turn the motor off at a particular time such that the piston stops at or approximately at the optimal parking position, is difficult and frequently inaccurate.
Accordingly, improved methods for determining optimal parking positions for compressor pistons, and associated compressors, are desired in the art. In particular, methods which facilitate real time updates of a stored optimal parking position for a compressor piston during operation, and which provide relatively accurate optimal parking position determinations, would be advantageous.